ABSTRACT Broadband near‐infrared phosphors are essential for advancing energy‐efficient phosphor‐converted light‐emitting diodes in applications such as night vision and bioimaging. While Mo 4+ doped 0D metal halides offer a promising route to near‐infrared emission, achieving both high efficiency and stability remains challenging. Herein, we report a mixed‐cation strategy to synthesize Mo 4+ ‐doped (Rb 1− x Cs x ) 2 HfCl 6 vacancy‐ordered double perovskites, which exhibit broadband near‐infrared emission centered at 925 nm with a full width at half‐maximum over 180 nm. The optimized composition delivers a high photoluminescence quantum yield of 82.89% under 298 nm excitation and 77.64% under 763 nm excitation. Density functional theory and experiments confirm the formation of a thermodynamically stable Rb + /Cs + alloy, enabling the material to retain 80.5% of its room‐temperature photoluminescence intensity at 150°C. A prototype NIR pc‐LED is fabricated, demonstrating its potential for sensing and imaging. This work opens new horizons for optimizing the luminescence efficiency and stability of broadband near‐infrared luminescent metal halides.
Hu et al. (2025) studied this question.